Telephone system



Oct; 8, 1929.

MURPHY 1,730,981'

TELEPHONE SYSTEM Filed Oct. 20, 1927 5) www i subscribers line.

Patented Oct. 8., 1929 UNITED STATES PATENT OFFICE PAUL B. MURPHY, OF NYACK, NEW YORK, ASSIGNOR TO BELL TELEPHONE LABORA- TORIES, INCORPORATED,y OF NEW YORK, N. Y., A CORPORATION OF NEW YORK TELEPHONE SYSTEM Application filed October 20, 1927. Serial No. 227,339.y

This invention relates to telephone systems and particularly to improvements in the control of automatic switches over transmission lines. f f

Its object is to simplify the equipment used at one end of a transmission line for conditioning and controlling switching apparatus at the other end of the line.

Heretofore various arrangements have been proposed, such as operators keys and interi'upters for sending preliminary signals over a toll line to condition switches at the distant end for the reception of switch operating impulses. f

According to the present invention these devices are eliminated and an impulse transmitter provided which, on its first operation, sends impulses over the line at a rate differing from the rate of interruption of the impulse contacts to condition the switches at the distant end and which, on subsequent operations, sends impulses at the same rate at which said contacts are interrupted to selectively operate the switches. Where the line is equipped with repeaters or other devices which interfere with the transmission of direct current, a source of relatively high frequency alternating current is used to supply the impulses sent over the line by said impulse transmitter.

The invention has been illustrated in the accompanying drawing in which:

Fig. 1 shows it applied to a circuit arraiigement at a subscribers station and infwhich;

Fig. 2 shows it applied to a circuit arrangement at an operators position.

The operation of the systems shown in these two figures will now be described in detail. In Fig. 1, 1 indicates the usual subscribers telephone set, 2 a subscribers dial and 3 a This line may terminate at an automatic oflice in switching equipments thereat for establishing connections to wanted subscribers lines. The equipment at the automatic ofce may be such thaty a wanted subscribers line is selected by means of high frequency alternating current impulses along the general character of the system disclosed in my Patent No. 1,573,991, issued February 23, 1926. In this patent a preliminary impulse of high frequency current of `1000 cycles per second interrupted forty times per second prepares the switching equipment for the reception of and control by regular dialing yimpulses representing the wanted subscribers number. The dialing impulses consist of high frequency alternating current of 1000 cycles per second. It should be kunderstood that in Fig. 1 the preliminary impulse for preparingy the automatic equipment at the central oiiicc may comprise an impulse of 1000 cycle current interrupted at a rate of twenty interruptions per second and that the system described in the abovementioned patent may readily be modified to respond to such preliminary impulse. As the automatic equipment at the central office does not form any part of this invention, it has not been shown or described However, in Fig. 2 an arrangement has been shown for the operator at the central oi'ice that may actually be substituted for the operators equipment shown in this patent to dial the preliminary impulse of 1000 cycle current interrupted the forty times per second rate.

Referring now particularly to Fig. 1, to transmit the preliminary impulse and dial the number of the wanted subscriber, the subscriber yof set 1; first, lifts his receiver from the hook which causes the operation of the relay 4 through the closure of the subscribers loop to the central oliice in a manner well known in the art; second, he actuates dial 2 for a complete revolution and then operates` it in accordance with the digits of the wanted subscribers number. The first operation of the dial in this manner causes the operation of relay 5 on the movement of the dial from normal. The circuit for the operation of relay 5 may be traced from battery, through the winding of relay 5, the operated contacts of off-normal Contact 6 to ground. Relay 5 in operating closes ay locking circuit for itself from battery through itswinding and upper inn er armature an d front contact to ground at the armature and front contact of relay 4. Relay 5 in operating also connects the 1000 cycle alternating'current source at 10 across the tip and ring conductors of line 3 at the upper and lower outer armatures and front contacts of this relay.

Another circuit closed by relay 5 is as fol- Cil lows battery, left hand winding of the trans'- former 11, lower armature and back contact of relay 13, lower middle armature and front contact of relay 5, through the pulsing contacts of dial 2 to ground. During the return movement to normal, these pulsing contacts 12 are operated in the usual manner causing the current through the primary winding of transformer 11 to be interrupted at the rate of approximately ten times per second. Current of approximately ten cycles per second will therefore be induced in the secondary winding of transformer 11 andV through the relay 14. Inasmuch as relay 14 is not polarized it will operate on both halves Vof the wave from the circuit through its lower winding, right hand winding of transformer 11 and condenser 15. Consequently, relay 1e will opera-te at twice the rate of operation of the pulsing contacts 12, or twenty times per second. This relay will therefore interrupt the application of current from lthe 1000 cycle source 10 applied across the conductors of line 3 twenty times per second. This preliminary impulse of 1000 cycle current interrupted at twenty times per second prepares the switches at the central oice as hereinbefore mentioned.

When the dial returns to normal after the iirst operation, it closes a' circuit for the operation of relay 13 as follows battery, winding of relay 13, inner lower armature and frontcontact of relay 5, upper normally( closed contacts of the off-normal contacts 6 to ground. Relay 13 closes a locking circuit for itself as follows: from battery through the winding and upper armature and front contact of relay 13 to ground at the armature and front contact of relay 11. r1he operation of relay 13' opens the original circuit for the primary winding of the transformer 11 and closes a circuit for the upper winding of relay 1d as follows: battery, upper winding of relay 14, lower armature and front Contact or" relay 13, middle 'lower armature and front contact of relay 5, impulsing contacts 12 to ground. lielay 14 is thereby operated and y opens the bridge for the`1000 cycle source 10 across the line 3.

When now the dial 2`is operated in accordance with the 'digits of the wanted subscribers line, relay 14 will release for each operation of the pulsing contacts 12 and thus connect the 1000 cycle current source 10 across the line 3 to transmit the desired number of impulses for each digit. These impulses select the wanted subscribers line and connect it through to line 3 in the usual manner. When the calling subscriber at 1 hangs up his receiver to release the connection, relay 4c is released causing the release of relays 5 and 13 and relay 13 in turn releases relay 1d to restore the circuit to normal.

Referring now particularly to Fig. 2, the circuits of this figure may be'substituted for the circuit marked 150 of F ig. 1 in the above mentioned patent. The relays marked 152, 153, 154, 155, 158, 161 and 162 correspond to the correspondingly numbered relays in this patemy and their functions will not be described here. rlhese functions merely relate to certain supervisory provisions in this circuit wliich are identical with those shown in the above mentioned patent and that form no part or" this invention. The lead marked corresponds to the lead in the above mentioned patent connected to key 35. The leads 101 d 102 correspond to the leads connected to the left hand armatures of relay 36, while the leads marked 103 and 101 correspond to leads Ll1 and L12 in the above mentioned patent.

llfhen the operator actuates her dial 106 for a complete revolution to transmit the preliminary impulses, a circuit is closed, as the oii-normal contacts 107 are actuated for the operation of relay 109 over a circuit as follows: battery, winding of relay 109, left hand armature and back contact of relay 103, the closed contacts and o-normal contacts 106 to ground. y1`he operation of relay 109 is for the purpose of establishing a connection through lead 100 to ground at the key 35 of Fig. 1 of tl]e above mentioned patent for re- 103. relay dees not operate this time as its circuit is shortened loy the ground at the contacts 107. Un the return of the `i .l 106 to normal the pulsing contact-s 110 teruptedI t ppronimately ten tin es second to release and operate relay 111 at the same rate. rEhe operation and release of relay 111 closes and opens an obvious circuit for the left hand winding of transformer 112. These circuit interruptions in turn induce current impulses in the circuit for relay 113 at twice the rate of the interruptions of the circuit for the left hand winding of transformer 112. That is, relay 113 is operated at twenty times per second. The operation and release of relay 113 closes and opens the circuit through the left hand winding of the repeating coil 11e at this rate and consequently causes-the circuit for the left hand wind-A ing of relay 115 to be energized at forty times per second. r1`hat is, relay 115 is operated and released at forty times per second for the complete operation of the dial 10'. Current from the 1000 cycle source 116 is therefore alternately applied and removed from the circuit comprising leads 103 and 104e at the corresponding rate. These two leads may be connected as shown in the above mentioned pate' t to the line for the preparing of the automatic equipment for the reception of dialing impulses.

When the dial 106 returns to normal, the -1it through the ofi-normal contacts K y 103 is removed so that this relay now operate from battery, through tie winding of relay 100, winding of relay CII armature and front contact of relay 109 to the ground at the key 35 in the above mentioned patent. This relay in operating opens the normal operating circuit for relay 109 but this relay is held operated in series with relay 108.

On the subsequent operations of the dial 106 for the selection of the Wanted subscribers number, the pulsing contacts 110 which are now connected in a circuit from ground through the right hand armature and front contact of relay 108, and the right hand Winding of relay 115 to battery, cause relay 115 to be alternately operated and released in accordance with the setting of the dial. Consequently, current from the 1000 cycle source 110 is now applied to the line in accordance With the Wanted subscribers number. When the dialing equipment shoWn in Fig. 2 is no further required it Will be released from the circuit shown in Fig. lof the above mentioned patent by the release of key 35 Which auses the release of relays 107 and 108.

It should be understood that While this invention has only been shown in connection with two different circuit arrangements it could readily be applied in a variety of different systems Without departing from the spirit thereof.

VYhat is claimed is:

1. In a telephone system, a line, a dial, a source of current, means responsive to one operation of the dial for transmitting impulses oit current from said source over said line at a rate different from the rate of interruptions produced by the dial contacts, and means responsive to subsequent operation of the dial for transmitting impulses of current 'from said source at the same rate at which the dial contacts are interrupted.

2. In a telephone system, a line, a dial, a source of current, means responsive to the movement of the dial from normal for connecting said source to the line, means responsive during the return movement of the dial to normal tor interrupting said connection at a rate diiierent from the rate of interruptions of the dial contacts, means responsive on the return of the dial to normal for Opening said connection from the source to the line, and means responsive to subsequent operations of the dial for closing said connection each time the dial contacts are interrupted.

3. In a telephone system, a line, a dial, a source ot current, and means responsive during an operation of the dial and controlled by the dial contacts for transmitting impulses from said source at a rate di'tering from but bearing a certain relation to the rate of interruptions of said dial contacts.

il. In a telephone system, a line, a dial, a source o'l current, and means controlled directly by the contacts of the dial for transmitting impulses of current from said source at a multiple of the number of interruptions of the dial contacts during one operation of the dial and for transmitting impulses of current from said source at the rate of interruptions of the dial contacts during subsequent operations of the dial.

5. In a telephone system, a line, a dial, a source of current, means responsive to the movement of the dial from normal and controlled by the olf-normal contacts of said dial for connecting said source to the line, means responsive during the return movement of the dial to normal and controlled by the pulsing contacts of the said dial for interrupting said connection a number of times Which is a multiple of thenumber of interruptions of said pulsing contacts, and means responsive to the return ot' the dial to normal and controlled bythe pulsing contacts for opening said connection.

6. In a telephone system, a line, a dial, a source of alternating current, means responsive to one operation of the dial for transmitting over said line impulses from said source, each impulse comprising a given numberof current alter-nations, and means responsive to subsequent operation oi said dial for transmitting over said line impulses from said source, each such impulse comprising a number of current alternations diilering from the number involved in said first impulses.

7 In a telephone system, a line, a dial, s source of alternating current,means responsive to one operation of the dial for transmitting over said line impulses from said source, each impulse comprising a given number of current alter-nations which bears a deiinite relation to the rate of interruptions of the dial contacts, and means responsive to subsequent operation oit said dial for transmitting over said line impulses from said source, each such impulse comprising a given number of current alternations differing from the number involved in said first impulses.

In Witness whereof, I hereunto subscribe my name this 19th day of October', A. D. 1927.

' PAUL B. MURPHY. 

